The field of the invention is that of ad hoc communications networks.
The invention relates more precisely to broadcasting information in an ad hoc network formed dynamically by a plurality of communicating mobile nodes moving on traffic lanes of a particular geographical network in which each node can be located.
The invention finds a preferred but non-limiting application in vehicular ad hoc networks (VANETs), in which each communication node consists of a vehicle moving along traffic lanes of a road network, in particular in urban environments.
Broadcasting information in this type of network has many applications, such as broadcasting information relating to road traffic for intelligent transportation systems in order to improve driver safety and comfort.
In a paper entitled “Urban multihop broadcast protocol for inter-vehicle communications systems” published in VANET '04: Proceedings of the 1st ACM International Workshop on Vehicular Ad Hoc Networks, Philadelphia, Pa., USA: ACM Press, September 2004, pp. 76-85, G. Korkmaz, E. Ekici, F. Özgüner, and U. Özgöner describe a multihop protocol for broadcasting data packets for an inter-vehicular communications system suitable for an urban environment.
That protocol uses a combination of two types of packet broadcasting: local broadcasting at each junction and directional broadcasting between two successive junctions.
It provides for the use of fixed repeaters placed at each junction to transfer data packets to the nodes located at a junction during local broadcasting. When a node conveying a packet sent by the repeater leaves a junction and enters a traffic lane, it participates in directional broadcasting. During directional broadcasting, the node conveying the packet sends the packet to its most distant neighbor node, which becomes a sender node and in turn sends the packet to its most distant neighbor, without using information relating to the topology of the network.
A drawback of this type of approach is that it requires the installation of fixed repeaters at each junction. This is laborious and can be costly, especially if the road network covered by the ad hoc inter-vehicular network is very large.